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Q1. Explain the differences between Server-side and Client-side code? Ans. server side code will execute at server (where the website is hosted) end, & all the business logic will execute at server end where as client side code will execute at client side (usually written in javascript, vbscript, jscript) at browser end. Q2. What type of code (server or client) is found in a Code-Behind class? Ans. Server side code. Q3. How to make sure that value is entered in an asp:Textbox control? Ans. Use a RequiredFieldValidator control. Q4. Which property of a validation control is used to associate it with a server control on that page? Ans. ControlToValidate property. Q5. How would you implement inheritance using VB.NET & C#? Ans. C# Derived Class : Baseclass VB.NEt : Derived Class Inherits Baseclass Q6. Which method is invoked on the DataAdapter control to load the generated dataset with data? Ans. Fill() method. Q7. What method is used to explicitly kill a user's session? Ans. Session.Abandon() Q8. What property within the asp:gridview control is changed to bind columns manually? Ans. Autogenerated columns is set to false Q9. Which method is used to redirect the user to another page without performing a round trip to the client? Ans. Server.Transfer method. Q10. How do we use different versions of private assemblies in same application without re-build? Ans.Inside the Assemblyinfo.cs or Assemblyinfo.vb file, we need to specify assembly version. assembly: AssemblyVersion Q11. Is it possible to debug java-script in .NET IDE? If yes, how? Ans. Yes, simply write "debugger" statement at the point where the breakpoint needs to be set within the javascript code and also enable javascript debugging in

the browser property settings. Q12. How many ways can we maintain the state of a page? Ans.u 1. Client Side - Query string, hidden variables, viewstate, cookies 2. Server side - application , cache, context, session, database Q13. What is the use of a multicast delegate? Ans. A multicast delegate may be used to call more than one method. Q14. What is the use of a private constructor? Ans. A private constructor may be used to prevent the creation of an instance for a class. Q15. What is the use of Singleton pattern? Ans. A Singleton pattern is used to make sure that only one instance of a class exists. Q16. When do we use a DOM parser and when do we use a SAX parser? Ans. The DOM Approach is useful for small documents in which the program needs to process a large portion of the document whereas the SAX approach is useful for large documents in which the program only needs to process a small portion of the document. Q17. Will the finally block be executed if an exception has not occurred? Ans.Yes it will execute. Q18. What is a Dataset? Ans. A dataset is an in memory database kind of object that can hold database information in a disconnected environment. Q19. Is XML a case-sensitive markup language? Ans. Yes. Q20. What is an .ashx file? Ans. It is a web handler file that produces output to be consumed by an xml consumer client (rather than a browser). Q21. What is encapsulation? Ans. Encapsulation is the OOPs concept of binding the attributes and behaviors in a class, hiding the implementation of the class and exposing the functionality. Q22. What is Overloading? Ans. When we add a new method with the same name in a same/derived class but with different number/types of parameters, the concept is called overload and this

ultimately implements Polymorphism. Q23. What is Overriding? Ans. When we need to provide different implementation of a method in a child class than the one provided by base class, we define the same method with same signatures in the child class and this is called overriding. Q24. What is a Delegate? Ans. A delegate is a strongly typed function pointer object that encapsulates a reference to a method, and so the function that needs to be invoked may be called at runtime. Q25. Is String a Reference Type or Value Type in .NET? Ans. String is a Reference Type object. Q26. What is a Satellite Assembly? Ans. Satellite assemblies contain resource files corresponding to a locale (Culture + Language) and these assemblies are used in deploying an application globally for different languages. Q27. What are the different types of assemblies and what is their use? Ans. Private, Public(also called shared) and Satellite Assemblies. Q28. Are MSIL and CIL the same thing? Ans. Yes, CIL is the new name for MSIL. Q29. What is the base class of all web forms? Ans. System.Web.UI.Page Q30. How to add a client side event to a server control? Ans. Example... BtnSubmit.Attributes.Add("onclick","javascript:fnSomeFunctionInJavascript()"); Q31. How to register a client side script from code-behind? Ans. Use the Page.RegisterClientScriptBlock method in the server side code to register the script that may be built using a StringBuilder. Q32. Can a single .NET DLL contain multiple classes? Ans. Yes, a single .NET DLL may contain any number of classes within it. Q33. What is DLL Hell? Ans. DLL Hell is the name given to the problem of old unmanaged DLL's due to which there was a possibility of version conflict among the DLLs.

Q34. can we put a break statement in a finally block? Ans. The finally block cannot have the break, continue, return and goto statements. Q35. What is a CompositeControl in .NET? Ans. CompositeControl is an abstract class in .NET that is inherited by those web controls that contain child controls within them. Q36. Which control in asp.net is used to display data from an xml file and then displayed using XSLT? Ans. Use the asp:Xml control and set its DocumentSource property for associating an xml file, and set its TransformSource property to set the xml control's xsl file for the XSLT transformation. Q37. Can we run ASP.NET 1.1 application and ASP.NET 2.0 application on the same computer? Ans. Yes, though changes in the IIS in the properties for the site have to be made during deployment of each. Q38. What are the new features in .NET 2.0? Ans. Plenty of new controls, Generics, anonymous methods, partial classes, iterators, property visibility (separate visibility for get and set) and static classes. Q39. Can we pop a MessageBox in a web application? Ans. Yes, though this is done clientside using an alert, prompt or confirm or by opening a new web page that looks like a messagebox. Q40. What is managed data? Ans. The data for which the memory management is taken care by .Net runtime’s garbage collector, and this includes tasks for allocation de-allocation. Q41. How to instruct the garbage collector to collect unreferenced data? Ans. We may call the garbage collector to collect unreferenced data by executing the System.GC.Collect() method. Q42. How can we set the Focus on a control in ASP.NET? Ans. txtBox123.Focus(); OR Page.SetFocus(NameOfControl); Q43. What are Partial Classes in Asp.Net 2.0? Ans. In .NET 2.0, a class definition may be split into multiple physical files but partial classes do not make any difference to the compiler as during compile time, the compiler groups all the partial classes and treats them as a single class. Q44. How to set the default button on a Web Form? Ans. <asp:form id="form1" runat="server" defaultbutton="btnGo"/>

Q45.Can we force the garbage collector to run? Ans. Yes, using the System.GC.Collect(), the garbage collector is forced to run in case required to do so. Q46. What is Boxing and Unboxing? Ans. Boxing is the process where any value type can be implicitly converted to a reference type object while Unboxing is the opposite of boxing process where the reference type is converted to a value type. Q47. What is Code Access security? What is CAS in .NET? Ans. CAS is the feature of the .NET security model that determines whether an application or a piece of code is permitted to run and decide the resources it can use while running. Q48. What is Multi-tasking? Ans. It is a feature of operating systems through which multiple programs may run on the operating system at the same time, just like a scenario where a Notepad, a Calculator and the Control Panel are open at the same time. Q49. What is Multi-threading? Ans. When an application performs different tasks at the same time, the application is said to exhibit multithreading as several threads of a process are running.2 Q50. What is a Thread? Ans. A thread is an activity started by a process and its the basic unit to which an operating system allocates processor resources. Q51. What does AddressOf in VB.NET operator do? Ans. The AddressOf operator is used in VB.NET to create a delegate object to a method in order to point to it. Q52. How to refer to the current thread of a method in .NET? Ans. In order to refer to the current thread in .NET, the Thread.CurrentThread method can be used. It is a public static property. Q53. How to pause the execution of a thread in .NET? Ans. The thread execution can be paused by invoking the Thread.Sleep(IntegerValue) method where IntegerValue is an integer that determines the milliseconds time frame for which the thread in context has to sleep.

Q54. How can we force a thread to sleep for an infinite period? Ans. Call the Thread.Interupt() method.

Q55. What is Suspend and Resume in .NET Threading? Ans. Just like a song may be paused and played using a music player, a thread may be paused using Thread.Suspend method and may be started again using the Thread.Resume method. Note that sleep method immediately forces the thread to sleep whereas the suspend method waits for the thread to be in a persistable position before pausing its activity. Q56. How can we prevent a deadlock in .Net threading? Ans. Using methods like Monitoring, Interlocked classes, Wait handles, Event raising from between threads, using the ThreadState property. Q57. What is Ajax? Ans. Asyncronous Javascript and XML - Ajax is a combination of client side technologies that sets up asynchronous communication between the user interface and the web server so that partial page rendering occur instead of complete page postbacks. Q58. What is XmlHttpRequest in Ajax? Ans. It is an object in Javascript that allows the browser to communicate to a web server asynchronously without making a postback. Q59. What are the different modes of storing an ASP.NET session? Ans. InProc (the session state is stored in the memory space of the Aspnet_wp.exe process but the session information is lost when IIS reboots), StateServer (the Session state is serialized and stored in a separate process call Viewstate is an object in .NET that automatically persists control setting values across the multiple requests for the same page and it is internally maintained as a hidden field on the web page though its hashed for security reasons. Q60. What is a delegate in .NET? Ans. A delegate in .NET is a class that can have a reference to a method, and this class has a signature that can refer only those methods that have a signature which complies with the class. Q61. Is a delegate a type-safe functions pointer? Ans. Yes Q62. What is the return type of an event in .NET? Ans. There is No return type of an event in .NET. Q63. Is it possible to specify an access specifier to an event in .NET? Ans. Yes, though they are public by default.

Q64. Is it possible to create a shared event in .NET? Ans. Yes, but shared events may only be raised by shared methods. Q65. How to prevent overriding of a class in .NET? Ans. Use the keyword NotOverridable in VB.NET and sealed in C#. Q66. How to prevent inheritance of a class in .NET? Ans. Use the keyword NotInheritable in VB.NET and sealed in C#. Q67. What is the purpose of the MustInherit keyword in VB.NET? Ans. MustInherit keyword in VB.NET is used to create an abstract class. Q68. What is the access modifier of a member function of in an Interface created in .NET? Ans. It is always public, we cant use any other modifier other than the public modifier for the member functions of an Interface. Q69. What does the virtual keyword in C# mean? Ans. The virtual keyword signifies that the method and property may be overridden. Q70. How to create a new unique ID for a control? Ans. ControlName.ID = "ControlName" + Guid.NewGuid().ToString(); //Make use of the Guid class Q71A. What is a HashTable in .NET? Ans. A Hashtable is an object that implements the IDictionary interface, and can be used to store key value pairs. The key may be used as the index to access the values for that index. Q71B. What is an ArrayList in .NET? Ans. Arraylist object is used to store a list of values in the form of a list, such that the size of the arraylist can be increased and decreased dynamically, and moreover, it may hold items of different types. Items in an arraylist may be accessed using an index. Q72. What is the value of the first item in an Enum? 0 or 1? Ans. 0 Q73. Can we achieve operator overloading in VB.NET? Ans. Yes, it is supported in the .NET 2.0 version, the "operator" keyword is used. Q74. What is the use of Finalize method in .NET? Ans. .NET Garbage collector performs all the clean up activity of the managed objects, and so the finalize method is usually used to free up the unmanaged

objects like File objects, Windows API objects, Database connection objects, COM objects etc. Q75. How do you save all the data in a dataset in .NET? Ans. Use the AcceptChanges method which commits all the changes made to the dataset since last time Acceptchanges was performed. Q76. Is there a way to suppress the finalize process inside the garbage collector forcibly in .NET? Ans. Use the GC.SuppressFinalize() method. Q77. What is the use of the dispose() method in .NET? Ans. The Dispose method in .NET belongs to IDisposable interface and it is best used to release unmanaged objects like File objects, Windows API objects, Database connection objects, COM objects etc from the memory. Its performance is better than the finalize() method. Q78. Is it possible to have have different access modifiers on the get and set methods of a property in .NET? Ans. No we can not have different modifiers of a common property, which means that if the access modifier of a property's get method is protected, and it must be protected for the set method as well. Q79. In .NET, is it possible for two catch blocks to be executed in one go? Ans. This is NOT possible because once the correct catch block is executed then the code flow goes to the finally block. Q80. Is there any difference between System.String and System.StringBuilder classes? Ans. System.String is immutable by nature whereas System.StringBuilder can have a mutable string in which plenty of processes may be performed. Q81. What technique is used to figure out that the page request is a postback? Ans. The IsPostBack property of the page object may be used to check whether the page request is a postback or not. IsPostBack property is of the type Boolean. Q82. Which event of the ASP.NET page life cycle completely loads all the controls on the web page? Ans. The Page_load event of the ASP.NET page life cycle assures that all controls are completely loaded. Even though the controls are also accessible in Page_Init event but here, the viewstate is incomplete. Q83. How is ViewState information persisted across postbacks in an

ASP.NET webpage? Ans. Using HTML Hidden Fields, ASP.NET creates a hidden field with an ID="__VIEWSTATE" and the value of the page's viewstate is encoded (hashed) for security. Q84. What is the ValidationSummary control in ASP.NET used for? Ans. The ValidationSummary control in ASP.NET displays summary of all the current validation errors. Q85. What is AutoPostBack feature in ASP.NET? Ans. In case it is required for a server side control to postback when any of its event is triggered, then the AutoPostBack property of this control is set to true. Q86. What is the difference between Web.config and Machine.Config in .NET? Ans. Web.config file is used to make the settings to a web application, whereas Machine.config file is used to make settings to all ASP.NET applications on a server(the server machine). Q87. What is the difference between a session object and an application object? Ans. A session object can persist information between HTTP requests for a particular user, whereas an application object can be used globally for all the users. Q88. Which control has a faster performance, Repeater or Datalist? Ans. Repeater. Q89. Which control has a faster performance, Datagrid or Datalist? Ans. Datalist. Q90. How to we add customized columns in a Gridview in ASP.NET? Ans. Make use of the TemplateField column. Q91. Is it possible to stop the clientside validation of an entire page? Ans. Set Page.Validate = false; Q92. Is it possible to disable client side script in validators? Ans. Yes. simply EnableClientScript = false. Q93. How do we enable tracing in .NET applications? Ans. <%@ Page Trace="true" %> Q94. How to kill a user session in ASP.NET? Ans. Use the Session.abandon() method.

Q95. Is it possible to perform forms authentication with cookies disabled on a browser? Ans. Yes, it is possible. Q96. What are the steps to use a checkbox in a gridview? Ans. <ItemTemplate> <asp:CheckBox id="CheckBox1" runat="server" AutoPostBack="True" OnCheckedChanged="Check_Clicked"></asp:CheckBox> </ItemTemplate> Q97. What are design patterns in .NET? Ans. A Design pattern is a repeatitive solution to a repeatitive problem in the design of a software architecture. Q98. What is difference between dataset and datareader in ADO.NET? Ans. A DataReader provides a forward-only and read-only access to data, while the DataSet object can carry more than one table and at the same time hold the relationships between the tables. Also note that a DataReader is used in a connected architecture whereas a Dataset is used in a disconnected architecture. Q99. Can connection strings be stored in web.config? Ans. Yes, in fact this is the best place to store the connection string information. Q100. Whats the difference between web.config and app.config? Ans. Web.config is used for web based asp.net applications whereas app.config is used for windows based applications.

Q1 - Write a query to find the total number of rows in a table A1 - Select count(*) from t_employee; Q2 - Write a query to eliminate duplicate records in the results of a table A2 - Select distinct * from t_employee;

Q3 - Write a query to insert a record into a table A3 - Insert into t_employee values ('empid35','Barack','Obama'); Q4 - Write a query to delete a record from a table A4 - delete from t_employee where id='empid35'; Q5 - Write a query to display a row using index A5 - For this, the indexed column of the table needs to be set as a parameter in the where clause select * from t_employee where id='43'; Q6 - Write a query to fetch the highest record in a table, based on a record, say salary field in the t_salary table A6 - Select max(salary) from t_salary; Q7 - Write a query to fetch the first 3 characters of the field designation from the table t_employee A7 - Select substr(designation,1,3) from t_employee; -- Note here that the substr function has been used. Q8 - Write a query to concatenate two fields, say Designation and Department belonging to a table t_employee Select Designation + ‘ ‘ + Department from t_employee; Q9 -What is the difference between UNION and UNION ALL in SQL? A9 - UNION is an SQL keyword used to merge the results of two or more tables using a Select statement, containing the same fields, with removed duplicate values. UNION ALL does the same, however it persists duplicate values. Q10 - If there are 4 SQL Select statements joined using Union and Union All, how many times should a Union be used to remove duplicate rows? A10 - One time. Q11 - What is the difference between IN and BETWEEN, that are used inside a WHERE clause? A11 - The BETWEEN clause is used to fetch a range of values, whereas the IN clause fetches data from a list of specified values.

Q12 - Explain the use of the ‘LIKE’ keyword used in the WHERE clause? Explain wildcard characters in SQL. A12 - LIKE is used for partial string matches. The symbol ‘%’ ( for a string of any character ) and ‘_’ (for any single character ) are the two wild card characters used in SQL. Q13 - What is the need to use a LIKE statement? A13 - When a partial search is required in a scencario, where for instance, you need to find all employees with the last name having the sequence of characters "gat", then you may use the following query, to match a search criteria: Select empid, firstname, lastname from t_employee where lastname like ‘%gats%’ This might search all employees with last name containing the character sequence 'gats' like Gates, Gatsby, Gatsburg, Sogatsky, etc. % is used to represent remaining all characters in the name. This query fetches all records contains gats in the e middle of the string. Q14 - Explain the use of the by GROUP BY and the HAVING clause. A14 - The GROUP BY partitions the selected rows on the distinct values of the column on which the group by has been done. In tandem, the HAVING selects groups which match the criteria specified. Q15 - In a table t_employee, the department column is nullable. Write a query to fetch employees which are not assigned a department yet. A11. Select empid, firstname, lastname from t_employee where department is null; Q16 -What are the large objects supported by oracle and db2? What are the large objects supported in MS SQL? A16 - In Oracle and DB2 BLOB , CLOB ( Binary Large Objects, Character Large Objects) are used. In MS SQL - the data types are image and varbinary. Q17 - Whats the capacity of the image data type in MS SQL? A17 - Variable-length binary data with a maximum length of 2^31 - 1 (2,147,483,647) bytes. Q18 - Whats the capacity of varbinary data type in MS SQL? A18 - Variable-length binary data with a maximum length of 8,000 bytes.

Q19 - What’s the difference between a primary key and a unique key? A19 - Both Primary key and Unique key enforce the uniqueness of a column on which they are defined. However, a Primary key does not allow nulls, whereas unique key allow nulls. Q20 - What are the different types of joins in SQL? INNER JOIN OUTER JOIN LEFT OUTER JOIN RIGHT OUTER JOIN FULL OUTER JOIN INNER JOIN Read here for more http://www.dotnetuncle.com/SQL/What-is-Join-in-SQL-types-ofjoins.aspx Q21 - What is a Self join? A21 - A join created by joining two or more instances of a same table. Query: Select A.firstname , B.firstname from t_employee A, t_employee B where A.supervisor_id = B.employee_id; Q22 - What is a transaction and ACID? A22 - Transaction - A transaction is a logical unit of work. All steps must be committed or rolled back. ACID - Atomicity, Consistency, Isolation and Durability, these are the unique entities of a transaction. What are DDL statements in SQL? Explain the Create, Alter and Drop commands. In SQL, DDL stands for Data Definition Language. It is the part of SQL programming language that deals with the construction and alteration of database structures like tables, views, and further the entities inside these tables like columns. It may be used to set the properties of columns as well.

Questions on Differences between Q. 1. What is the difference between abstract class and interface? If a class is to serve the purpose of providing common fields and members to all subclasses, we create an Abstract class. For creating an abstract class, we make use of the abstract keyword. Such a class cannot be instantiated. Syntax below: abstract public class Vehicle { } Above, an abstract class named Vehicle has been defined. We may use the fields, properties and member functions defined within this abstract class to create child classes like Car, Truck, Bike etc. that inherit the features defined within the abstract class. To prevent directly creating an instance of the class Vehicle, we make use of the abstract keyword. To use the definitions defined in the abstract class, the child class inherits from the abstract class, and then instances of the Child class may be easily created. Further, we may define abstract methods within an abstract class (analogous to C+ + pure virtual functions) when we wish to define a method that does not have any default implementation. Its then in the hands of the descendant class to provide the details of the method. There may be any number of abstract methods in an abstract class. We define an abstract method using the abstract keyword. If we do not use the abstract keyword, and use the virtual keyword instead, we may provide an implementation of the method that can be used by the child class, but this is not an abstract method. Remember, abstract class can have an abstract method, that does not have any implementation, for which we use the abstract keyword, OR the abstract class may have a virtual method, that can have an implementation, and can be overriden in the child class as well, using the override keyword. Read example below Example: Abstract Class with Abstract method namespace Automobiles { public abstract class Vehicle { public abstract void Speed() //No Implementation here, only definition } } Example: Abstract Class with Virtual method namespace Automobiles { public abstract class Vehicle { public virtual void Speed() //Can have an implementation, that may be overriden in child class { ...

} } Public class Car : Vehicle { Public override void Speed() //Here, we override whatever implementation is there in the abstract class { ... //Child class implementation of the method Speed() } } } An Interface is a collection of semantically related abstract members. An interface expresses through the members it defines, the behaviors that a class needs to support. An interface is defined using the keyword interface. The members defined in an interface contain only definition, no implementation. The members of an interface are all public by default, any other access specifier cannot be used. See code below: Public interface IVehicle //As a convention, an interface is prefixed by letter I { Boolean HasFourWheels() } Time to discuss the Difference between Abstract Class and Interface 1) A class may inherit only one abstract class, but may implement multiple number of Interfaces. Say a class named Car needs to inherit some basic features of a vehicle, it may inherit from an Aabstract class named Vehicle. A car may be of any kind, it may be a vintage car, a sedan, a coupe, or a racing car. For these kind of requirements, say a car needs to have only two seats (means it is a coupe), then the class Car needs to implement a member field from an interface, that we make, say ICoupe. 2) Members of an abstract class may have any access modifier, but members of an interface are public by default, and cant have any other access modifier. 3) Abstract class methods may OR may not have an implementation, while methods in an Interface only have a definition, no implementation.

Explain the access specifiers Public, Private, Protected, Friend, Internal, Default The main purpose of using access specifiers is to provide security to the applications. The availability (scope) of the member objects of a class may be controlled using access specifiers. 1. PUBLIC As the name specifies, it can be accessed from anywhere. If a member of a class is

defined as public then it can be accessed anywhere in the class as well as outside the class. This means that objects can access and modify public fields, properties, methods. 2. PRIVATE As the name suggests, it can't be accessed outside the class. Its the private property of the class and can be accessed only by the members of the class. 3. FRIEND/INTERNAL Friend & Internal mean the same. Friend is used in VB.NET. Internal is used in C#. Friends can be accessed by all classes within an assembly but not from outside the assembly. 4. PROTECTED Protected variables can be used within the class as well as the classes that inherites this class. 5. PROTECTED FRIEND/PROTECTED INTERNAL The Protected Friend can be accessed by Members of the Assembly or the inheriting class, and ofcourse, within the class itself. 6. DEFAULT A Default property is a single property of a class that can be set as the default. This allows developers that use your class to work more easily with your default property because they do not need to make a direct reference to the property. Default properties cannot be initialized as Shared/Static or Private and all must be accepted at least on argument or parameter. Default properties do not promote good code readability, so use this option sparingly. Whats the difference between a class and an object? In any object Oriented language, an object is the backbone of everything that we see. A class is a blueprint that describes how an instance of it (object) will behave. To create a class, we define it in a "Code File", with an extension *.cs or *.vb. We make use of the keyword class. Example Lets create a class named Laptop public class Laptop { private string sbrand; public Laptop() {} public Laptop(string name) { sbrand = name; } }

From our code that references this class, we write... Laptop lp = new Laptop("Lenovo"); //Passing a variable to the class constructor Once the class object is created, the object may be used to invoke the member functions defined within the class. We may allocate any number of objects using the new keyword. The new keyword returns a reference to an object on the heap. This reference is not to the actual object itself. The variable being refered is stored on a stack for usage in the application. When we allocate an object to a heap, its managed by the .NET runtime. The garbage collector takes care of the object by removing it from the heap, when it is no longer reachable by any part of the code.

What is the difference between Shared and Static? They both mean the same. Shared is used in VB.NET. Static is used in C#. When the static keyword is used to declare a class, the member in context must be directly invoked from the class, rather than from the instance. Consider the following example //Consider writing the following line of code... Console obj = new Console(); obj.Writeline("Vishal likes static members"); //This line does'nt print //This does'nt work, because WriteLine is a static method defined in the class Console //The Console class is a static class To use static members, give a reference to the exact class, as an instance in this case won't work. To make this work, write... Console.Writeline("Vishal likes static members"); To work with members of static classes, no need to create their instances. Static Member - A class member declared with the keyword static is a static member. A static member is owned by the class, not by its instances (objects of the class). Note that static members are actually class members, while non-static members are instance members (means they are owned by the instances). Both in C# & VB.NET, we may create static/shared events, properties, fields and functions. Note Indexers in C# cannot be declared static. Note Static member functions cannot access non-static members directly. What is the difference between value type and reference type? Can a value type contain NULL values?

In simple words, all value based types are allocated on the stack, while all reference based types are allocated on the heap. What does this mean? A value type contains the actual value. A reference type contains a reference to the value. When a value type is assigned to another value type, it is copied. When a reference type is assigned to another reference type, a reference is assigned to the value. By saying stack, we mean things are kept one on top of the other. We keep track of each value at the top. By saying heap, we mean things are kept in a mashed order. We keep track of each value by its address, that is referenced by a pointer to it. All value types are implicitly derived from System.ValueType. This class actually overrides the implementation in System.Object, the base class for all objects which is a reference type itself. Data types like integers, floating point numbers, character data, Boolean values, Enumerations and Structures are examples of Value Types. Classes, Strings, Arrays are examples of Reference Types. A value type may not contain NULL values. Reference types may contain NULL values. It is not possible to derive new types from Value Types. This is possible in Reference types. However, Value Types like Structures can implement interfaces. What is the difference between a DLL and an EXE? In .NET, an assembly may become a DLL or an EXE. Yet, there is a major underlying difference between the two. An EXE is an executable file, that may run on its own. Its independant. Where as a DLL is a Dynamic Link Library, that binds to an exe, or another DLL at runtime. A DLL has an exposed interface, through which members of the assembly may be accessed by those objects that require it. A DLL runs in tandem with the application space in memory, as the application references it. Whereas an EXE is independant, and runs as an independant process. What is the difference between String and StringBuilder? Both String and StringBuilder are classes used to handle strings. The most common operation with a string is concatenation. This activity has to be performed very efficiently. When we use the "String" object to concatenate two strings, the first string is combined to the other string by creating a new copy in the memory as a string object, and then the old string is deleted. This process is a little long. Hence we say "Strings are immutable".

When we make use of the "StringBuilder" object, the Append method is used. This means, an insertion is done on the existing string. Operation on StringBuilder object is faster than String operations, as the copy is done to the same location. Usage of StringBuilder is more efficient in case large amounts of string manipulations have to be performed. What is the difference between Web Services and Remoting? Both Remoting and Web Services are ways of communication between applications. Remoting - In remoting, the applications involved in the communication process may be located on the same computer, different computers in a same or different network. In remoting, both applications know about each other. A proxy of an application object is created on the other application. Web Services - Communication between applications using web services is platform independent and programming independent. The application that consumes the web service, simply accesses it, without needing to know how this web service has actually been implemented & created. Here are some of the major differences: * ASP.NET Web Services may be accessed using HTTP only. Remoting objects may be accessed over any protocol like TCP, SMTP, HTTP * Web Service are Stateless, whereas Remoting has support for both stateless and with-state environment, which is achieved using Singleton and Singlecall activation * ASP.NET provides good support to create Web Services. They are easy to deploy. In comparison, Remoting is little complex. * Web services may be considered very reliable, due to the fact that they are hosted on IIS. In remoting, if IIS is'nt used, then methods like plumbing have to be used to ensure the application reliability. * In .NET, when we create an application that consumes a web service, the web service may or may not be built using .NET. But while implementing Remoting in .NET, both the applications must be built in .NET. * Using web services, only a limited number of types may be serialized (XML). Using Remoting, objects like SOAP objects, Binary objects & XML Objects may be serialized. What is the difference between ExecuteScalar and ExecuteNonQuery? What is ExecuteReader? ExecuteScalar - Returns only one value after execution of the query. It returns the first field in the first row. This is very light-weight and is perfect when all your query asks for is one item. This would be excellent for receiving a count of records (Select Count(*)) in an sql statement, or for any query where only one specific field in one column is required.

ExecuteNonQuery - This method returns no data at all. It is used majorly with Inserts and Updates of tables. It is used for execution of DML commands. Example: SqlCommand cmd = new SqlCommand("Insert Into t_SomeTable Values('1','2')",con); //note that con is the connection object con.Open(); cmd.ExecuteNonQuery(); //The SQL Insert Statement gets executed ExecuteReader - This method returns a DataReader which is filled with the data that is retrieved using the command object. This is known as a forward-only retrieval of records. It uses our SQL statement to read through the table from the first to the last record.

What is the difference between a DataReader and Dataset in ADO.NET? A DataReader works in a connected environment, whereas DataSet works in a disconnected environment. A DataReader object represents a forward only, read only access to data from a source. It implements IDataReader & IDataRecord interfaces. For example, The SQLDataReader class can read rows from tables in a SQL Server data source. It is returned by the ExecuteReader method of the SQLCommand class, typically as a result of a SQL Select statement. The DataReader class' HasRows property can be called to determine whether the DataReader retrieved any rows from the source. This can be used before using the Read method to check whether any data has been retrieved. Example Dim objCmd as New SqlCommand("Select * from t_Employees", objCon) objCon.Open() Dim objReader as SqlDataReader objReader = objCom.ExecuteReader(CommandBehavior.CloseConnection) If objReader.HasRows = True then Do While objReader.Read() ListBox1.Items.Add(objReader.GetString(0) & vbTab & objReader.GetInt16(1)) Loop End If objReader.Close() (NOTE: XmlReader object is used for Forward only Read only access of XML). A DataSet represents an in-memory cache of data consisting of any number of inter-related DataTable objects. A DataTable object represents a tabular block of in-

memory data. Further, a DataRow represents a single row of a DataTable object. A Dataset is like a mini-database engine, but its data is stored in the memory. To query the data in a DataSet, we can use a DataView object.

Example Dim objCon as SqlConnection = New SqlConnection("server=(local);database=NameOfYourDb;user id=sa; password=;) Dim da as New SqlDataAdapter Dim ds as DataSet = New DataSet da.SelectCommand.Connection = objCon 'The Data Adapter manages on its own, opening & closing of connection object da.SelectCommand.CommandText = "Select * from t_SomeTable" da.Fill(ds,"YourTableName") Suppose you want to bind the data in this dataset to a gridview Gridview1.DataSource = ds Gridview1.DataMember = "YourTableName" Gridview1.Databind()

What is the difference between System .Array.CopyTo and System.Array.Clone in .NET? The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. What is the difference between a Thread and Process? A process is a collection of virtual memory space, code, data, and system resources. A thread is code that is to be serially executed within a process. A processor executes threads, not processes, so each application has at least one process, and a process always has at least one thread of execution, known as the primary thread. A process can have multiple threads in addition to the primary thread. Prior to the introduction of multiple threads of execution, applications were all designed to run on a single thread of execution. When a thread begins to execute, it continues until it is killed or until it is interrupted by a thread with higher priority (by a user action or the kernel’s thread scheduler). Each thread can run separate sections of code, or multiple threads can execute the same section of code. Threads executing the same block of code maintain separate stacks. Each thread in a process shares that process’s global variables and resources.

What is the difference between Trace and Debug? Trace and Debug - There are two main classes that deal with tracing - Debug and Trace. They both work in a similar way - the difference is that tracing from the Debug class only works in builds that have the DEBUG symbol defined, whereas tracing from the Trace class only works in builds that have the TRACE symbol defined. Typically this means that you should use System.Diagnostics.Trace.WriteLine for tracing that you want to work in debug and release builds, and System.Diagnostics.Debug.WriteLine for tracing that you want to work only in debug builds. Tracing is actually the process of collecting information about the program's execution. Debugging is the process of finding & fixing errors in our program. Tracing is the ability of an application to generate information about its own execution. The idea is that subsequent analysis of this information may help us understand why a part of the application is not behaving as it should and allow identification of the source of the error. We shall look at two different ways of implementing tracing in .NET via the System.Web.TraceContext class via the System.Diagnostics.Trace and System.Diagnostics.Debug classes. Tracing can be thought of as a better alternative to the response.writes we used to put in our classic ASP3.0 code to help debug pages. If we set the Tracing attribute of the Page Directive to True, then Tracing is enabled. The output is appended in the web form output. Messeges can be displayed in the Trace output using Trace.Warn & Trace.Write. NOTE The only difference between Trace.Warn & Trace.Write is that the former has output in red color. If the trace is false, there is another way to enable tracing. This is done through the application level. We can use the web.config file and set the trace attribute to true. Here we can set <trace enabled=false .../> Note that the Page Directive Trace attribute has precedence over th application level trace attribute of web.config. While using application level tracing, we can view the trace output in the trace.axd file of the project.

What is the difference between Authorization and Authentication? Both Authentication and Authorization are concepts of providing permission to users to maintain different levels of security, as per the application requirement. Authentication is the mechanism whereby systems may securely identify their users. Authentication systems depend on some unique bit of information known only to the individual being authenticated and the authentication system.

Authorization is the mechanism by which a system determines what level of access a particular authenticated user should have to secured resources controlled by the system. When a user logs on to an application/system, the user is first Authenticated, and then Authorized. ASP.NET has 3 ways to Authenticate a user: 1) Forms Authentication 2) Windows Authentication 3) Passport Authentication (This is obsolete in .NET 2.0) The 4th way is "None" (means no authentication) The Authentication Provider performs the task of verifying the credentials of the user ans decides whether a user is authenticated or not. The authentication may be set using the web.config file. Windows Authentication provider is the default authentication provider for ASP.NET applications . When a user using this authentication logs in to an application, the credentials are matched with the Windows domain through IIS. There are 4 types of Windows Authentication methods: 1) Anonymous Authentication - IIS allows any user 2) Basic Authentication - A windows username and password has to be sent across the network (in plain text format, hence not very secure). 3) Digest Authentication - Same as Basic Authentication, but the credentials are encrypted. Works only on IE 5 or above 4) Integrated Windows Authentication - Relies on Kerberos technology, with strong credential encryption Forms Authentication - This authentication relies on code written by a developer, where credentials are matched against a database. Credentials are entered on web forms, and are matched with the database table that contains the user information. Authorization in .NET - There are two types: FileAuthorization - this depends on the NTFS system for granting permission UrlAuthorization - Authorization rules may be explicitly specified in web.config for different web URLs.

What is the difference between a Public Assembly and a Private Assembly? An assembly is the basic building block in .NET. It is the compiled format of a class, that contains Metadata, Manisfest & Intermediate Language code.

An assembly may be either Public or Private. A public assembly means the same as Shared Assembly. Private Assembly - This type of assembly is used by a single application. It is stored in the application's directory or the applications sub-directory. There is no version constraint in a private assembly. Shared Assembly or Public Assembly - A shared assembly has version constraint. It is stored in the Global Assembly Cache (GAC). GAC is a repository of shared assemblies maintained by the .NET runtime. It is located at C:\Windows\Assembly OR C:\Winnt\Assembly. The shared assemblies may be used by many applications. To make an assembly a shared assembly, it has to be strongly named. In order to share an assembly with many applications, it must have a strong name. A Strong Name assembly is an assembly that has its own identity, through its version and uniqueness. In order to convert a private assembly to a shared assembly, i.e. to create a strongly named assembly, follow the steps below... 1) Create a strong key using the sn.exe tool. This is used to created a cryptographic key pair. The key pair that is generated by the Strong Name tool can be kept in a file or we can store it our your local machine's Crytographic Service Provider (CSP). For this, goto the .NET command interpreter, and type the following... sn -k C:\samplekey.snk This will create a strong key and save it to the location C:\samplekey.snk 2) If the key is stored in a file, just like we have done above, we use the attribute AssemblyKeyFileAttribute. This belongs to the namespace System.Reflection.AssemblyKeyFileAttribute. If the key was in the CSP, we would make use of System.Reflection.AssemblyKeyNameAttribute. Go to the assemblyinfo.vb file of your project. Open this file. Make the following changes in this file... <assembly: assemblykeyfileattribute("C:\samplekey.snk")> We may write this in our code as well, like this... Imports System.Reflection <assembly: assemblykeyfileattribute("C:\samplekey.snk")> Namespace StrongName Public class Sample End Class End Namespace

3) Build your project. Your assembly is now strongly named. Installing the Shared assembly in GAC... Go to .NET command interpreter, use the tool gacutil.exe Type the following... gacutil /i sampleclass.dll To uninstall it, use... gacutil /u sampleclass.dll. Visual Studio.NET provides a GUI tool for viewing all shared assemblies in the GAC. What is the difference between a Class Library and a Namespace? Class Library is another major entity of the .NET Framework (the other being the CLR). This library gives the program access to runtime environment. The class library consists of lots of prewritten code that all the applications created in .NET will use. The code for all the elements like forms, controls actually comes from the class library. The main class library in .NET is mscorlib.dll. This library contains a large number of core types that encapsulate a wide variety of common tasks. When a .NET application, there is automatic access to this library. We may view the class libraries provided by the .NET Framework by seeing the Global Assembly Cache (Go to C:\Windows\Assembly OR C:\Winnt\Assembly). Namespace is a grouping of related types contained in an assembly. For example, the System.Drawing namespace consists of classes, methods that are grouped together to achieve similar tasks. Note that a single assembly like mscorlib.dll may contain any number of namespaces. In fact, namespaces may be nested (means a namespace within a namespace) to arrange classes in a hierarchical fashion. Also note that any language, that works on the .NET environment, targets the same set of namespaces & types provided by the .NET framework. What is the difference between ADO and ADO.NET? The old ADO (ActiveX Data Object) has evolved to ADO.NET in the .NET Framework. The ADO.NET object is a lightweight object. The ADO Recordset was a huge object in ADO. It provided the ability to support multiple types of cursors. It provided fast lightweight "firehose" cursor and also supported a disconnected client-side cursor that supported tracking, optimistic locking, and automatic batch updates of a central database. However, all of this functionality was difficult to customize. ADO.NET breaks the functionality of the ADO object to multiple classes, thereby allowing a focused approach to developing code. The ADO.NET DataReader is equivalent to the "firehose" cursor. The DataSet is a disconnected cache with tracking and control binding functionality. The DataAdapter provides the ability to completely customize how the central data store is updated with the changes to a DataSet. Whats the difference betweeen Structure, Class and Enumeration ? Structures and Enumerations are Value-Types. This means, the data that they contain is stored as a stack on the memory. Classes are Reference-Types, means they are stored as a heap on the memory.

Structures are implicitly derived from a class called System.ValueType. The purpose of System.ValueType is to override the virtual methods defined by System.Object. So when the runtime encounters a type derived from System.ValueType, then stack allocation is achieved. When we allocate a structure type, we may also use the new keyword. We may even make a constructor of a structure, but, remember, A No-argument constructor for a structure is not possible. The structure's constructor should always have a parameter. So if we define the following structure struct MyStruct { public int y,z; } and we create a structure type MyStruct st = new MyStruct(); In case of a class, no-argument constructors are possible. Class is defined using the class keyword. A struct cannot have an instance field, whereas a class can. class A { int x = 5; //No error ... } struct { int x = 5; //Syntax Error } A class can inherit from one class (Multiple inheritance not possible). A Structure cannot inherit from a structure. Enum is the keyword used to define an enumeration. An enumeration is a distinct type consisting of a set of named constants called the enumerator list. Every enumeration has an underlying type. The default type is "int". Note: char cant be the underlying data type for enum. First value in enum has value 0, each consequent item is increased by 1. enum colors {red, green, blue, yellow}; Here, red is 0, green is 1, blue is 2 and so on. An explicit casting is required to convert an enum value to its underlying type

int x = (int)colors.yellow;

Whats the difference between MSIL and CIL? MSIL is the name given to the intermediate language in .NET Framework Beta, 1.0 and 1.1. From version 2.0 onwards, the intermediate language is called CIL. We can say, MSIL is the old name. MSIL stands for Microsoft Intermediate Language. CIL stands for Common Intermediate Language. Its actually a low level human readable language implementation of CLI. There is not much difference between the two. Compilers like vbc.exe and csc.exe compile the code into intermediate language. CIL is the name submitted by Microsoft to the European Computer Manufacturer's Association(ECMA) as a standard. Difference between Bugs, Exceptions and End User Errors ? Humans are bound to make errors, and programmers are humAns. Applications may crash or stop running because of different reasons. The crash may happen during the application development OR during production when the application is already released. Now this hiccup may be categorized in three ways: 1) Bugs - When the cause of the error is because of a mistake done by a developer, its called a bug. A developer may be well experienced but still may write bad code by mistake. For instance, a declared file object may not be disposed, and may later cause a memory leak, well thats a bug. Normally, during development of enterprise applications, bugs are caught by Testers and categorized based on their criticality. But there may be times when even the Testing team might miss out on catching a bug. Well, thats danger! 2) Exceptions - An exception may be a System Exception or an Application Exception. Now say, a file being parsed by the code has been deleted by some one from the location being searched, then a "File Not Found" exception may crop up. Such exceptions are usually handled by well written code by using Exception Handlers. These errors are usually caused at runtime. They may be difficult to prevent at times, but surely may be handled by good code. There might be a scene where the programmer may only catch the exception through good code but may not prevent it. 3) End User Errors - An error may be invoked by an input made by the end user. For example, an invalid string may be entered in a Textbox that expects a number. These types of errors may be handled using controls like RegularExpressionValidator, or code that handles the keyboard, mouse, stylus input. These errors if not handled efficiently by the developer, may cause

terrible nightmares. For example, an application may be hacked or damaged using SQL injections, if at all, input boxes allow bad input that may crack the code. What is LINQ? Language Integrated Query (LINQ), pronounced simply as 'link' is a component of the Microsoft .NET Framework that enhances .NET based languages with data Querying power. The syntax is kind of similar to SQL. LINQ has been released along with the .NET 3.5 Framework. It is one of the most powerful features of .NET 3.5. It serves the purpose of querying objects. LINQ comprises a series of operators, which are used to query, filter and project data in arrays, enumerable classes, relational databases and XML. In order to query data, the data needs to be encapsulated as an object. In case the data source is not an object, it first needs to be converted to an object in order for LINQ to query it. LINQ has its own Query Processing Engine. The information returned by a LINQ query is a collection of in-memory object which may be enumerated. The LINQ concept treats the data source as an Object, rather than a Database. So we may say, its an object that is queried. LINQ may query any type of data source, like:
• • • • •


querying querying querying querying querying

SQL (MS SQL Server supported). Datasets (Querying is possible on Datasets and DataTables) ORM Solution Objects (In-memory data may be queried) XML (Querying is possible on XML data source

LINQ supports querying to those objects that implement the IEnumerable Interface. In the example code below, LINQ is being used to query a simple array containing integers: int[] values = new int[] {4,5,6,7}; var output = from i in values where i < 4 orderby i select i; foreach(int j in values) Response.Write(j); Note: For writing code in C# that understands the LINQ syntax, the System.Linq namespace needs to be used. What is OOPs? OOPs - Object Oriented Programming Languages & Systems Everything in the world is an object. The type of the object may vary. In OOPS, we

get the power to create objects of our own, as & when required. OOPs is a programming methodology where each entity is an object. It is a method of computer programming where entities of related data together with routines associated with it are treated as one object in the program. What is a class member? What is an object? The entities like events, properties, fields and functions encapsulated within a class are called class members. A constructor of a class that resides within it is also a form of a class member. When we instantiate a class in order to use its encapsulated class members, this instantiated class entity is called the object. Difference between class & object What is a property? What is an event? Property - A property is a thing that describes the features of an object. A property is a piece of data contained within a class that has an exposed interface for reading/writing. Looking at this definition, we might think we could declare a public variable in a class and call it a property. While this assumption is somewhat valid, the real technical term for a public variable in a class is a field. The main difference between a field and a property is in the inclusion of an interface. We make use of Get and Set keywords while working with properties. We prefix the variables used within this code block with an underscore. Value is a keyword, that holds the value which is being retrieved or set.ss="a"> Private _Color As String Public Property Color() Get Return _Color End Get Set(ByVal Value) _Color = Value End Set End Property Event - An action that an object does. When something happens, we say an event has happened. For example, when a button is clicked, we say it is the click( ) event. When a mouse hovers on an image, we say the mouseover( ) event has taken place. What is the virtual keyword used for? Virtual - If a base class method is to be overriden, it is defined using the keyword virtual (otherwise the sealed keyword is used to prevent overriding). Note that the class member method may be overriden even if the virtual keyword

is not used, but its usage makes the code more transparent & meaningful. In VB.NET , we may use the overridable keyword for this purpose. When the override keyword is used to override the virtual method, in a scenario where the base class method is required in a child class along with the overriden method, then the base keyword may be used to access the parent class member. The following code example will make the usage more clear. public class Employee { public virtual void SetBasic(float money) //This method may be overriden { Basic += money; } } public class Manager : Employee { public override void SetBasic(float money) //This method is being overriden { float managerIncentive = 10000; base.SetSalary(money + managerIncentive); //Calling base class method } } What is the difference between Casting and Parsing? Casting is just switching between different primitive data types. Example: 'int' to 'short'. Casting is an internal process that was designed to reduce overheads and execution errors. Casting requires an object. A cast of an object reference requires validation that the Object actually is of the target type.

Parsing is converting strings to primitive data types such as 'int'. Example: String to ‘int’. Parsing is the process of analyzing an input sequence in order to determine its grammatical structure. Parse requires a string for input.

Parsing always has the possibility of a bad format exception, which is a checked exception you should do something with. What is the difference between Int32 and int? There is no difference between these two. int is just an alias for Int32. Same apply for string and String. What is a constructor? Explain the New Keyword. What is a Private Constructor? Constructor - A constructor is a function with the same name as that of the class. The Default Constructor of a class is without an argument. The default constructor ensures that every member data is initialized to a default value. Constructors provide a way for classes to initialize a state for their members. Note that constructors dont have a return type(not even void). public SomeClass() { Console.Writeline("Vishal says, Default Constructor is called"); } \ public SomeClass(string str) { Console.Writeline("Vishal says, Custom Constructor is called" + str); } When a custom constructor is defined, the Default Constructor is not called. A constructor may also be overloaded. New - This keyword may be used as a modifier and as an operator. When used as an operator, it creates an object on a heap to invoke constructors. When used an a modifier, it hides an inherited member from the base class member. As an operator, it can be used to create an object and then to invoke the constructor of the class. See example below. Example SomeClass objSomeClass = new SomeClass(); //Creating a class object and invoking its constructor float amount = new float(); //Creating an object of the type, and invoking its constructor As a modifier, it is used to explicitly hide a member from the base class. See example.

Example public class MamaClass { public void SomeMethod() { ... } } public class BabyClass : MamaClass { new public void SomeMethod() { .... } } Private Constructor - When a constructor is created with a private specifier, it is not possible for other classes to derive from this class, neither is it possible to create an instance of this class. They are usually used in classes that contain static members only. It is also used to create Singleton classes. What is a static constructor? Static Constructor - It is a special type of constructor, introduced with C#. It gets called before the creation of the first object of a class(probably at the time of loading an assembly). See example below. Example: public class SomeClass() { static SomeClass() { //Static members may be accessed from here //Code for Initialization } } While creating a static constructor, a few things need to be kept in mind: * There is no access modifier require to define a static constructor * There may be only one static constructor in a class * The static constructor may not have any parameters * This constructor may only access the static members of the class * We may create more than one static constructor for a class Can a class be created without a constructor? No. In case we dont define the constructor, the class will access the no-argument constructor from its base class. The compiler will make this happen during compilation. What is Serialization? What is serializable attribute used for? Serialization - The process of converting an object into a stream of bytes. This stream of bytes can be persisted. Deserialization is an opposite process, which involves converting a stream of bytes into an object. Serialization is used usually during remoting (while transporting objects) and to persist file objecst & database

objects. .NET provides 2 ways for serializtion 1) XmlSerializer and 2) BinaryFormatter/SoapFormatter The XmlSerializer is used for Web Services. The BinaryFormatter & SoapFormatter is used for Remoting. While using XmlSerializer, it is required that the target class has parameter less constructors, has public read-write properties and has fields that can be serialized. The XmlSerializer has good support for XML documents. It can be used to construct objects from existing XML documents. The XmlSerializer enables us to serialize and deserialize objects to an XML format. SoapFormatter enables us to serialize & deserialize objects to SOAP format. They can serialize private and public fields of a class. The target class must be marked with the Serializable attribute. On deserialization, the constructor of the new object is not invoked. The BinaryFormatter has the same features as the SoapFormatter except that it formats data into binary format. The BinaryForamatter (and the SoapFormatter) has two main methods. Serialize and Deserialize. To serialize an object, we pass an instance of the stream and the object to the Serialize method. To Deserialize an object, you pass an instance of a stream to the Deserialize method. You can use the BinaryFormatter to serialize many, but not all, classes in the .NET Framework. For example, you can serialize ArrayLists, DataSets, and Arrays but not other objects, such as DataReaders or TextBox controls. To serialize a class, the class must have the Serializable attribute or implement the ISerializable interface. Note that the XmlSerializer captures only the public members of the class, whereas the BinaryFormatter & the SoapFormatter captures both the public & private members of the class. The output using the BinaryFormatter is quite compact, as the information is in binary format, whereas the XmlSerializer format is filled with XML tags. See example below... Imports System.IO Imports System.Runtime.Serialization.Formatters.Binary Dim colArrayList As ArrayListDim objFileStream As FileStreamDim objBinaryFormatter As BinaryFormattercolArrayList = New ArrayList() colArrayList.Add( "Whisky") colArrayList.Add( "Vodka") colArrayList.Add( "Brandy") objFileStream = New FileStream(MapPath("C:\myArrayList.data"), FileMode.Create) objBinaryFormatter = New BinaryFormatterobjBinaryFormatter.Serialize(objFileStream, colArrayList)objFileStream.Close() Here we see that an instance of the file stream (objFileStream) and an instance of the object (colArrayList) is passed to the Serialize method of the BinaryFormatter object (objBinaryFormatter). We also end up creating a file by the name

myArrayList.data on our hard-drive.In order to deserialize an object, see the code below… Dim colArrayList As ArrayListDim objFileStream As FileStreamDim objBinaryFormatter As BinaryFormatterDim strItem As String objFileStream = New FileStream( MapPath("myArrayList.data"), FileMode.Open ) objBinaryFormatter = New BinaryFormatter colArrayList = CType( objBinaryFormatter.Deserialize( objFileStream ), ArrayList ) objFileStream.Close() For Each strItem In colArrayList Response.Write( " " & strItem ) Next Here, CType takes in two parameters, the first parameter is the serialized object in the file stream format, and the second parameter is the desired type. Finally, the page iterates through all the elements of the ArrayList and displays the value of each element. XmlSerializer does not serialize instances of classes like Hashtable which implement the IDictionary interface. Serializable - This is a class attribute. When we use this attribute with a class, an instance of this class can be taken in whatever state it is, and write it to a disk. The class can then be deserialized, and the class will act as if it is simply stored in the memory. What is a delegate? What is a Multicast Delegate? Delegate - It is a type safe function pointer. It is a type that holds the reference of a method. A delegate may be used to call a method asynchronously. Multicast Delegate - it is a delegate that holds reference of more than one method. Multicast Delegates must have a return type of void. What is a DataView in ADO.NET? DataView - Just like we have Views in SQL (in our backend), we have DataView object in ADO.NET. A dataview object represents bindable, customized view of a DataTable object. Operations like Sorting, Filtering, Searching, Editing and Navigation may be performed on a DataView object. In scenarios like retrieval of a subset of data from a Datatable, we may make use of DataViews to get this data. Note that the DefaultView property of a DataTable returns the Default data view for the DataTable. In case a custom view of a DataTable has to be created on a DataView, then the RowFilter property of the DataView is set to the DefaultView. A dataview may also be used to sort data that resides in it in ascending or descending order. Below is code on how to sort data in a dataview in ascending or descending order...

DataView objdv = new DataView(); objdv.Sort("ColumnName Asc|Desc"); Why we use Temporary Tables? There are many cases where we need to create temporary tables in SQL Server and for various reasons. Such reasons may include:

 Breaking the logic of a large and complex SQL Statement in smaller portions of code.  Increase the performance of a SQL query, etc. There are two types of temporary tables:  Local temporary tables:  Only available to the current connection to the database for the current login They are dropped when the connection is closed

 Global temporary tables:   Available to any connection upon their creation They are dropped when the last connection using them is closed

Code Example – Local Temporary Table
CREATE TABLE #table_name ( column_name [DATATYPE] )

Code Example – Global Temporary Table
CREATE TABLE ##table_name ( column_name [DATATYPE] }

Temporary tables (local and global) are stored in the tempDB database.

How to insert value in a table in SQL Server that has a single column as Identity ? Ans : INSERT INTO MyTable DEFAULT VALUES What is SelectCommand in ADO.NET? Select Command Property - This property is used to hold the SQL command that is used to retrieve data from the data source. The CommandText and Connection are properties of the Select Command propety. CommandType is also a property of Select Command. See example below... Dim da as new SqlDataAdapter da.SelectCommand = New SqlCommand( ) With da.SelectCommand .Connection = objConnection .CommandText = "select * from employees" End With

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